• When all computers are connected to the same network cable, there are a number of structures which may be used. The bus topology below is simpler, and the tree topology is more flexible and versatile. This approach uses a single cable which is easy to add to

• The ring topology below shows a closed loop of cable which can be simple to implement, but limited in capabilities

• An enhanced ring topology is pictured below

• The figure below shows two ring networks, with a few possible devices hooked to them.

5.1 OSI NETWORK MODEL

• Advantages

Computers not necessarily from the same manufacturer

Allow computers to communicate information.

Sharing of equipment such as printers, disks, etc.

Programs can run on multiple machines improving performance

Access to machines with better/different resources.

• Several types: Ring, Star, Linear, Point-to-Point

• Local Area Network (LAN), Wide Area Network (WAN)

5.1.1 Why Use A Network?

• Medium for Communication:

Satellite link

Phone line

High Speed (Multiplexed) phone lines

Coax Cable

Fiber Optical Cable

Twisted pair cable

(Theoretically anything can be used)

• General OSI Diagram contains seven layers

5.1.1.1 - Physical Layer

• Physical layer is concerned with transmission of raw bits over a physical circuit.

• Deals with voltages, timing, connections, etc.

• Responsible for bit synchronization and the identification of a signal element as either a 0 or a 1.